Plasma process apparatus

ABSTRACT

A plasma process apparatus that utilizes plasma so as to perform a predetermined process on a substrate, and includes a process chamber that houses a substrate subjected to the predetermined plasma process; a microwave generator; a dielectric window attached to the process chamber and provided with a concave portion provided at an outer surface of the dielectric window opposite to the process chamber and a through hole penetrating the dielectric window to the process chamber; a microwave transmission line; and a first process gas supplying portion including a gas conduit including a first portion provided at a front end and a second portion having a larger diameter than the first portion, the gas conduit being inserted from outside of the process chamber such that the first portion is inserted in the through hole and the second portion is inserted in the concave portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/531,510 filed on Sep. 16, 2009, which claims thebenefit of priority of PCT International Application No.PCT/JP2008/056744 filed on Mar. 28, 2008, Japanese Patent ApplicationsNo. 2007-088407 and No. 2007-088653 filed with the Japanese PatentOffice on Mar. 29, 2007, United States Provisional Applications No.60/945,958 and No. 60/947,524 filed with the United States Patent andTrademark Office on Jun. 25, 2007 and Jul. 2, 2007, respectively, wherethe entire contents of all applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a microwave plasma process apparatusthat utilizes microwaves so as to carry out a predetermined plasmaprocess, specifically to a microwave plasma process apparatus thatsupplies microwave power to plasma in a process chamber throughelectromagnetic wave coupling.

2. Description of the Related Art

In plasma processes for fabricating semiconductor devices, liquidcrystal displays (LCD), and the like, radio frequency (RF) waves andmicrowaves are used so as to discharge or ionize a process gas in avacuum process chamber. An RF plasma apparatus mainly employs capacitycoupling where a pair of electrodes is located, one electrode inparallel with the other leaving an appropriate gap between theelectrodes in the process chamber. The RF waves are applied to one ofthe electrodes through a capacitor while the other electrode isgrounded. However, it is difficult to produce high density plasma atrelatively low pressures in the RF plasma apparatus. In addition, it isdisadvantageous in that device elements on a wafer are more frequentlydamaged during the plasma process because the RF plasma inherently hashigh electron temperatures.

In contrast, the microwave plasma apparatus is advantageous in that themicrowaves can produce high density plasma with low electrontemperatures at relatively low pressures. Additionally, the microwaveplasma apparatus has another advantage in that the microwave plasma canbe efficiently produced in a two-dimensional large area at a widerpressure range when a planar microwave introduction window through whichthe microwaves are introduced into the chamber is employed. Moreover,the microwave plasma apparatus may have a simple configuration as awhole because a magnetic field is not required (see Patent Document 1).

Patent Document 1: WO2005/045913 A1 (FIG. 1(A), FIG. 2)

In a microwave plasma process apparatus, since microwave plasma isgenerated from a process gas by introducing microwaves and the processgas into the process chamber, the ways of introducing the microwaves andthe process gas may be important factors that determine plasmacharacteristics and apparatus performance.

In the microwave plasma apparatus employing the planar microwaveintroduction window, there are two types of configurations in terms ofintroducing the process gas into the chamber. A first configuration hasa shower plate serving as the microwave introduction window that opposesa susceptor. In this configuration, the process gas is ejected downwardthrough plural gas ejection holes uniformly distributed in the showerplate.

On the other hand, a second configuration has one or plural gas ejectionholes formed in a side wall of the chamber in order to eject the processgas inward to a plasma region in the chamber.

In the first configuration, while it is advantageous in that the plasmacan be uniformly produced above the susceptor, the plasma density tendsto be lower, which leads to a low etching rate when the plasma processapparatus is an etcher, and an inefficient process as a whole. This isbecause the shower plate having plural gas ejection holes provides apathway through which the microwaves (electromagnetic waves) pass. Inaddition, such a configuration may cause a problem of contamination orthe like.

On the other hand, in the second configuration, since the microwaves donot pass through the gas ejection holes made in the side wall of thechamber, abnormal discharging is unlikely to take place. However, it isdifficult to diffuse the process gas uniformly in a radial direction,resulting in nonuniformly distributed plasma. Especially, since thechamber of a single-wafer plasma process apparatus is evacuated througha ring-like space between the susceptor and the inner wall of thechamber, the process gas tends to flow with nonuniform flow patterns inthe chamber. This is because the process gas, which is introduced so asto flow over the ring-like space, is affected by a flow of gas headedtoward an evacuation port below the ring-like space.

In addition, the process gas may be introduced into the process chamberthrough a gas ejection hole formed (pierced) through a dielectricwindow, which corresponds to a ceiling surface of the process chamberand opposes the susceptor.

In this case, since the dielectric window serves as a microwave,introduction window, that is, as a microwave propagation path, thereexists an electric field inside the dielectric window. Therefore, theprocess gas is exposed to the microwave electric field when flowingthrough the dielectric window, and thus may be ionized in a gas conduitin the dielectric window or near the gas ejection hole, which causesabnormal discharging. Such abnormal discharging may affect thedielectric window, so that the dielectric window is deteriorated ordamaged in a relatively short period of time, and may impair processperformance.

The present invention has been made in order to eliminate at least oneof the above-mentioned disadvantages, and provides a plasma processapparatus that can prevent abnormal discharging in a microwavetransmission line or radiation path, or a process gas ejection portion,so that plasma excellent in plasma density uniformity andcontrollability can be realized, thereby improving performance orquality of the plasma process.

In addition, the present invention may provide a plasma processapparatus in which plasma conditions or the plasma process can easilyand efficiently be monitored.

SUMMARY OF THE INVENTION

In order to eliminate any one of the above disadvantages, a first aspectof the present invention provides a plasma process apparatus thatprocesses a substrate utilizing plasma. The plasma process apparatusincludes a process chamber that houses a substrate subjected to apredetermined plasma process and may be evacuated to a reduced pressure;a microwave generator that generates microwaves for generating plasma; awaveguide pipe that transmits the microwaves from the microwavegenerator to the process chamber; a waveguide pipe/coaxial pipeconverter connected to one end of the waveguide pipe; a coaxial pipethat forms a line through which the microwaves are transmitted from thewaveguide pipe-coaxial pipe converter to the process chamber, wherein aninner conductive body of the coaxial pipe has a hollow portion; and afirst process gas supplying portion that supplies a process gas into theprocess chamber through the hollow portion of the inner conductive bodyof the coaxial pipe.

In the plasma process apparatus according to the first aspect, themicrowaves output from the microwave generator propagate through themicrowave transmission line including the waveguide pipe, the waveguidepipe/coaxial pipe converter, and the coaxial pipe, and are introducedinto the process chamber, while the process gas from the process gassupplier flows through the hollow portion of the inner conductive bodyof the coaxial pipe, circumventing a microwave propagation path, and isintroduced into the process chamber. The process gas is ionized by themicrowaves so as to generate plasma in the process chamber. Utilizingthe plasma, the substrate is processed.

As one of preferred embodiments of the present invention, the plasmaprocess apparatus according to the first aspect may further include asusceptor on which the substrate is placed in the process chamber, and adielectric window for introducing the microwaves into the processchamber, where the dielectric window serves as a ceiling surfaceopposing the susceptor. With this, the microwaves propagate as surfacewaves along a lower surface of the dielectric window, and the plasma isgenerated by the surface waves. In addition, the dielectric window maybe provided with a gas ejection opening that is in communication withthe hollow portion of the inner conductive body, where the process gascan be ejected from the gas ejection opening into the process chamber.

According to another preferred embodiment of the present invention, thedielectric window may be one of constituent elements of a planar antennato which an end portion of the coaxial pipe is connected. This planarantenna may be a slot antenna in order to efficiently generate highdensity plasma. Moreover, the planar antenna may include a radial lineslot antenna in order to generate a large area, or large diameterplasma.

According to another preferred embodiment of the present invention, thewaveguide pipe-coaxial pipe converter converts the transmission mode inthe waveguide pipe to a TEM mode in the coaxial pipe. Preferably, thewaveguide pipe may be square-shaped, where one end portion of the innerconductive body protrudes into the square-shaped waveguide pipe, and theprotruding end portion becomes thicker along the protruding direction inthe waveguide pipe-coaxial pipe converter. In addition, the hollowportion penetrates the inner conductive body of the coaxial pipe so asto allow a process gas to enter the hollow portion from an inlet openingmade in the protruding end portion of the inner conductive portion andto be ejected from a hole directed toward the interior of the processchamber. Moreover, the inner conductive body of the coaxial pipe mayinclude a coolant conduit through which a coolant may flow.

As another preferred embodiment of the present invention, the plasmaprocess apparatuses with at least one of the above-stated additionalfeatures may be provided with a second process gas supplying portionthat introduces a process gas into the chamber. The second process gassupplying portion may include a side wall eject hole from which theprocess gas is ejected toward a center portion of the process chamber.In this case, there may be provided a first flow rate control portionthat controls the flow rate of the process gas introduced into theprocess chamber through the first process gas supplying portion; and asecond flow rate control portion that controls the flow rate of theprocess gas introduced into the process chamber through the secondprocess gas supplying portion. With these, flow rates or the flow ratioof the process gasses introduced into the process chamber from thecorresponding process gas supplying portions are controlled, therebyimproving plasma density and distribution uniformity.

Furthermore, the plasma process apparatus according to other embodimentsof the present invention may include a radio frequency wave generatorthat applies radio frequency waves to the susceptor in order to generatea self bias voltage in the susceptor, or a magnetic field producingportion that surrounds the process chamber so as to produce a magneticfield around the process chamber, thereby causing electron cyclotronresonance in the plasma in the process chamber.

A second aspect of the present invention provides a plasma processapparatus in which a substrate subjected to a predetermined plasmaprocess is housed in a process chamber that may be evacuated to areduced pressure and plasma is generated from a process gas introducedinto the process chamber by introducing microwaves so as to perform thepredetermined plasma process on the substrate. The plasma processapparatus includes a microwave transmission line that transmits themicrowaves from a microwave generator to the process chamber, wherein apredetermined section of the microwave transmission line, the sectionincluding one end portion of the microwave transmission line, is formedof a coaxial line, and wherein an inner conductive body of the coaxialline is formed of a hollow pipe through which the process gas isintroduced into the process chamber.

A third aspect of the present invention provides a plasma processapparatus in which a substrate subjected to a predetermined plasmaprocess is housed in a process chamber that may be evacuated to areduced pressure and plasma is generated from a process gas introducedinto the process chamber by introducing microwaves so as to perform thepredetermined plasma process on the substrate. The plasma processapparatus includes a microwave transmission line that transmits themicrowaves from a microwave generator to the process chamber, wherein apredetermined section of the microwave transmission line, the sectionincluding one end portion of the microwave transmission line, is formedof a coaxial line whose inner conductive body is formed of a hollowpipe, and a monitor portion that monitors through the hollow pipe theplasma process performed in the process chamber.

In the plasma process apparatus according to the third aspect, themicrowaves output from the microwave generator propagate through themicrowave transmission line and are introduced into the process chamber,and the microwaves ionize the process gas so as to generate plasma inthe process chamber. The substrate is processed with the plasma. Whenthis process is performed, the plasma conditions or the plasma processin the process chamber can be monitored in-situ through the hollowportion of the inner conductive body of the coaxial pipe that mayconstitute at least one portion of the microwave transmission line bythe monitor portion. The monitor portion includes a plasma emissionmeasurement portion that spectroscopically measures emission of theplasma in the process chamber, an optical thickness measurement portionthat measures the thickness of a film on the substrate held on asusceptor in the process chamber, or a temperature sensor that measurestemperature inside the process chamber.

A fourth aspect of the present invention provides a plasma processapparatus that utilizes plasma so as to perform a predetermined processon a substrate. The plasma process apparatus includes a process chamberthat houses a substrate subjected to the predetermined plasma processand may be evacuated to a reduced pressure; a microwave generator thatgenerates microwaves for generating plasma; a dielectric window throughwhich the microwaves are introduced to the process chamber; a microwavetransmission line that transmits the microwaves from the microwavegenerator to the dielectric window; and a first process gas supplyingportion including a gas conduit that penetrates the dielectric window tothe process chamber in order to supply a process gas into the processchamber, the gas conduit being electrically conductive and grounded.

In the plasma process apparatus according to the fourth aspect of thepresent invention, the process gas from a process gas supplier of thefirst process gas supplying portion flows through the gas conduit, whichis grounded, and the dielectric window. Therefore, the process gas isnot exposed to an electric field due to the microwaves, and thusabnormal discharging can be prevented.

As one of preferred embodiments of the present invention, the gasconduit may penetrate one portion of the dielectric window, or plural ofthe gas conduits may penetrate corresponding plural portions of thedielectric window in the plasma process apparatus according to thefourth aspect. In view of a symmetric gas flow pattern, the gas conduitpreferably penetrates substantially the center of the dielectric windowwhen the gas conduit penetrates one portion of the dielectric window,and the plural portions are preferably located symmetrically in relationto substantially the center of the dielectric window.

As another preferred embodiment, a gas ejection portion of the gasconduit may protrude into the process chamber from the dielectricwindow, and specifically the gas ejection portion of the gas conduit ispreferably at a distance 10 mm or more from the dielectric window in theplasma process apparatus according to the fourth aspect. With thisconfiguration, the gas ejection portion can be located out of a plasmageneration region, or in a plasma diffusion region, so as to preventabnormal discharging around the gas ejection portion.

In addition, the plasma process apparatus according to the fourth aspectmay include a susceptor on which the substrate is placed in the processchamber, wherein the dielectric window serves as a ceiling surfaceopposing the susceptor. When the susceptor is provided, the plasmaprocess apparatus may preferably be provided with a radio frequency wavegenerator in order to apply radio frequency waves in order to generate aself bias voltage in the susceptor and thus attract ions in the plasma.

As another preferred embodiment of the present invention, the dielectricwindow is one of constituent elements of a planar antenna in the plasmaprocess apparatus according to the fourth aspect with at least one ofthe above-stated additional features. In this case, the planar antennamay include a radial line slot antenna. In addition, the microwavetransmission line includes a coaxial pipe whose end portion is connectedto the planer antenna.

As another preferred embodiment of the present invention, the gasconduit is formed in an inner conductive body in the plasma processapparatus according to the fourth aspect with at least one of theabove-stated additional features. In this case, the inner conductivebody preferably includes a hollow portion that may be used to allow gasto flow therethrough, the hollow portion extending along a center axisof the inner conductive body. Moreover, the gas conduit is preferably incommunication with the hollow portion and extends into the processchamber through a through hole made in the dielectric window. Withthese, the process gas can be introduced into the process chamberthrough an efficient and simplified gas introduction configuration.

As another preferred embodiment of the present invention, the microwavetransmission line includes a waveguide pipe one of whose ends isconnected to the microwave generator; a waveguide pipe/coaxial pipeconverter that couples another end of the waveguide pipe with one end ofthe coaxial pipe in order to convert one transmission mode ofelectromagnetic waves in the waveguide pipe to another transmission modein the coaxial pipe. In this case, the microwaves output from themicrowave generator propagate through the waveguide pipe, the waveguidepipe/coaxial pipe converter, and the coaxial pipe and are introducedinto the process chamber, while the process gas from the process gassupplying portion flows through the gas conduit, which is grounded,including the inner conductive body of the coaxial pipe, without beingexposed to the electric field due to the microwaves and is introducedinto the process chamber,

As another preferred embodiment of the present invention, the plasmaprocess apparatus according to the fourth aspect further includes asecond process gas supplying portion that introduces the process gasinto the chamber. The second process gas supplying portion may include aside wall eject hole from which the process gas is ejected toward acenter portion of the process chamber. In this case, the plasma processapparatus according to the fourth aspect further includes a first flowrate control portion that controls a flow rate of the process gasintroduced into the process chamber by the first process gas supplyingportion; and a second flow rate control portion that controls a flowrate of the process gas introduced into the process chamber by thesecond process gas supplying portion. With these, flow rates or the flowratio of the process gasses introduced into the process chamber from thecorresponding process gas supplying portion are controlled, therebyimproving plasma density and distribution uniformity.

A fifth aspect of the present invention provides a plasma processapparatus that utilizes plasma so as to perform a predetermined processon a substrate. The plasma process apparatus includes a process chamberthat houses a substrate subjected to the predetermined plasma process;an evacuation portion that evacuates the process chamber to a reducedpressure; a gas supplying line for supplying a process gas into theprocess chamber, the gas supplying line being electrically conductiveand grounded; a microwave generator that generates microwaves forgenerating plasma; a dielectric window through which the microwaves areintroduced to the process chamber, the dielectric window extendingaround the gas supplying line; and a microwave transmission line thattransmits the microwaves from the microwave generator to the dielectricwindow.

In the plasma process apparatus according to the fifth aspect, theprocess gas from a process gas supplier of the process gas supplyingportion flows through the gas supplying line, and is introduced into theprocess chamber, while the microwaves output from the microwavegenerator propagate through the microwave transmission line, and areintroduced into the process chamber through the dielectric windowextending around the gas supplying line. The process gas ejected from agas ejection opening of one end of the gas supplying line diffuses inthe chamber, and is ionized near the dielectric window by themicrowaves. Even in this plasma process apparatus, the end of the gassupplying line preferably protrudes from the dielectric window into theprocess chamber.

According to embodiments of the present invention, a plasma processapparatus that can prevent abnormal discharging in a microwavetransmission line or radiation path, or a process gas ejection portion,is provided, so that plasma excellent in plasma density uniformity andcontrollability can be realized, thereby improving performance orquality of the plasma process. In addition, a plasma process apparatusin which plasma conditions or a plasma process can easily be monitoredmay also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cut-open view of a plasma process apparatusaccording to a first embodiment of the present invention;

FIG. 2 schematically shows a primary portion of the plasma processapparatus shown in FIG. 1;

FIG. 3 is a plan view of a slot antenna used in the plasma processapparatus shown in FIG. 1;

FIG. 4 is a schematic cut-open view of a modification example of theplasma process apparatus according to the first embodiment of thepresent invention;

FIG. 5 is a schematic cut-open view of another modification example ofthe plasma process apparatus according to the first embodiment of thepresent invention;

FIG. 6 is a schematic cut-open view of a plasma process apparatusaccording to a second embodiment of the present invention;

FIG. 7 schematically shows a primary portion of the plasma processapparatus shown in FIG. 6;

FIG. 8 shows an experimental result of electron density distributionalong a direction from a dielectric window to a susceptor in the plasmaprocess apparatus shown in FIG. 6;

FIG. 9 shows an experimental result of electron temperature distributionalong a direction from a dielectric window to a susceptor in the plasmaprocess apparatus shown in FIG. 6; and

FIG. 10 is a schematic cut-open view of a modification example of theplasma process apparatus according to the second embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Non-limiting, exemplary embodiments of the present invention will now bedescribed with reference to the accompanying drawings. In the drawings,the same or corresponding reference marks are given to the same orcorresponding members or components. It is to be noted that the drawingsare illustrative of the invention, and there is no intention to indicatescale or relative proportions among the members or components, alone ortherebetween. Therefore, a specific thickness or size should bedetermined by a person having ordinary skill in the art in view of thefollowing non-limiting embodiments.

First Embodiment

FIG. 1 is a schematic cut-open view of a microwave plasma etchingapparatus 1 according to a first embodiment of the present invention.The microwave plasma etching apparatus 1, which is configured as aplanar SWP type plasma process apparatus, has a cylinder-shaped chamber(process chamber) 10 made of metal such as aluminum or stainless steel.The chamber 10 is grounded for security reasons.

First, components or members, which do not directly contribute togenerating the microwave plasma in the chamber 10 of the microwaveplasma etching apparatus 1, are described.

In a lower center portion of the chamber 10, there is a susceptor 12 onwhich a semiconductor wafer W (referred to as a wafer W below) isplaced. The susceptor 12 is horizontally supported by a cylindricalsupporting portion 14 extending upward from the bottom of the chamber10. The cylindrical supporting portion 14 is made of an insulatingmaterial. Additionally, the susceptor 12 is shaped into a circular plateand made of, for example, aluminum, serving also as a lower electrode towhich radio frequency waves are applied.

A ring-like evacuation pathway 18 is provided between the inner wall ofthe chamber 10 and another cylindrical supporting portion 16 thatextends upward from the bottom of the chamber 10 and along the outercircumferential surface of the cylindrical supporting portion 14. Thecylindrical supporting portion 16 is electrically conductive. Aring-like baffle plate 20 is arranged at a top portion (or an inletportion) of the evacuation pathway 18, and an evacuation port 22 isprovided below the evacuation pathway 18. In order to obtain uniform gasflow patterns distributed symmetrically in relation to the wafer W onthe susceptor 12 in the chamber 10, plural of the evacuation ports 22are preferably provided at equal angular intervals along acircumferential direction. Each of the evacuation ports 22 is connectedto an evacuation apparatus 26 through an evacuation pipe 24. Theevacuation apparatus 26 may have a vacuum pump such as a turbo molecularpump (TMP), which can evacuate the chamber 10 to a desired reducedpressure. A gate valve 28 is attached on an outer wall of the chamber10. The gate valve 28 opens and closes a transport opening through whichthe wafer W is transported into or out from the chamber 10.

The susceptor 12 is electrically connected to a radio frequency powersupply 30 that applies an RF bias voltage to the susceptor 12 through amatching unit 32 and a power feeding rod 34. The power supply 30outputs, at a predetermined electric power level, radio frequency waveshaving a relatively low frequency of, for example, 13.56 MHz. Such a lowfrequency is suitable to control the energy of ions to be attracted tothe wafer W on the susceptor 12. The matching unit 32 includes amatching element for matching output impedance of the power supply 30with impedance of a load including the electrode (susceptor), the plasmaproduced in the chamber 10, and the chamber 10. The matching element hasa blocking condenser for generating self bias.

An electrostatic chuck 36 is provided on the upper surface of thesusceptor 12. The electrostatic chuck 36 holds the wafer W byelectrostatic force on the susceptor 12. The electrostatic chuck 36 hasan electrode 36 a formed of an electroconductive film and a pair ofinsulating films 36 b, 36 c that sandwich the electrode 36 a. A DC powersupply 40 is electrically connected to the electrode 36 a via a switch42. The DC voltage applied to the electrostatic chuck 36 from the DCpower supply 40 produces a Coulomb force, which in turn holds the waferW onto the electrostatic chuck 36. Outside the electrostatic chuck 36, afocus ring 38 is provided in order to surround the wafer W.

A cooling medium chamber 44 is provided inside the susceptor 12. Thecooling medium chamber 44 has a ring-shape extending in acircumferential direction. A cooling medium or cooling water at apredetermined temperature is supplied to the cooling medium chamber 44through conduits 46, 48 from a chiller unit (not shown) so as tocirculate through the cooling medium chamber 44 and the conduits 46, 48.Due to the temperature-controlled cooling medium or the like, thetemperature of the wafer W on the electrostatic chuck 36 may becontrolled. In addition, a thermal conduction gas such as He gas issupplied between the wafer W and the electrostatic chuck through a gassupplying pipe 50 from a thermal conduction gas supplying portion (notshown). Moreover, the chamber 10 is provided with elevatable lift pins(not shown) that vertically penetrate the susceptor 12 and raise/lowerthe wafer W when the wafer W is loaded into or unloaded from the chamber10. The lift pins may be driven by an elevation mechanism (not shown).

Next, components or members which contribute to generating the microwaveplasma in the chamber 10 of the microwave plasma etching apparatus 1 aredescribed.

A planar antenna 55 is provided above the susceptor 12 in order tointroduce the microwaves into the chamber 11. The planar antenna 55includes a circular quartz plate 52 as a dielectric window and acircular radial line slot antenna (RLSA) 54. Specifically, the quartzplate 52 is hermetically attached to the chamber 10 and serves as aceiling surface of the chamber 11 that opposes the susceptor 12. TheRLSA 54 is located on the upper surface of the quartz plate 52, and hasplural slots distributed along concentric circles. The RLSA 54 iselectromagnetically coupled to a microwave transmission line 58 via aslow wave plate 56 formed of a dielectric material, for example, quartz.

The microwave transmission line 58 has a waveguide pipe 62, a waveguidepipe/coaxial pipe converter 64, and a coaxial pipe 66, and transmits themicrowaves output from a microwave generator 60 to the RLSA 54. Thewaveguide pipe 62 is formed of, for example, a square pipe, andtransmits the microwaves in a TE mode from the microwave generator 60through the waveguide pipe-coaxial pipe converter 64.

The waveguide pipe/coaxial pipe converter 64 couples the waveguide pipe62 with the coaxial pipe 66, and converts the TE mode microwaves in thewaveguide pipe 62 to TEM mode microwaves in the coaxial pipe 66. Theconverter 64 preferably has a larger diameter at an upper portionconnected to the waveguide pipe 62, and a smaller diameter at a lowerportion connected to an inner conductor 68 of the coaxial pipe 66 inorder to avoid a concentrated electromagnetic field, which may bepresent at high power transmission levels. In other words, the converter64 is preferably shaped into an inverted cone (or a door knob) as shownin FIGS. 1 and 2. The converter 64 may be referred to as an invertedcone portion 68 a for simplicity of explanation below.

The coaxial pipe 66 extends vertically downward from the converter 64 toan upper center portion of the chamber 10 and is coupled with the RLSA54. Specifically, the coaxial pipe 66 has an outer conductor 70 and theinner conductor 68. The outer conductor 70 is connected to the waveguidepipe 62 at the upper end and extends downward so as to reach the slowwave plate 56. The inner conductor 68 is connected to the converter 64at the upper end and extends downward so as to reach the RLSA 54. Themicrowaves propagate in the TEM mode between the inner conductor 68 andthe outer conductor 70.

The microwaves output from the microwave generator 60 are transmittedthrough the microwave transmission line 58 including the waveguide pipe62, the converter 64, and the coaxial pipe 66, and are supplied to theRLSA 54 passing through the slow wave plate 56. Then, the microwaves arespread in a radial direction in the slow wave plate 56 and emittedtoward the chamber 10 through the slots of the RLSA 54. The microwavesemitted through the slots propagate along the lower surface of thequartz plate 52 as surface waves, and ionize gas near the lower surfaceof the quartz plate 52, thereby generating plasma in the chamber 10.

An antenna back surface plate 72 is provided on the upper surface of theslow wave plate 56. The antenna back surface plate 72 is made of, forexample, aluminum. The antenna back surface plate 72 contains fluidconduits 74 to which a chiller unit (not shown) is connected so that acooling medium or cooling water at a predetermined temperature iscirculated through the conduits 74 and pipes 76, 78. Namely, the antennaback surface plate 72 serves as a cooling jacket that absorbs heatgenerated in the quartz plate 52 and transfers the heat to the outside.

As shown in FIG. 1, a gas conduit 80 is provided so as to go through theinner conductor 68 of the coaxial pipe 66 in this embodiment. Inaddition, a first gas supplying pipe 84 (FIG. 1) is connected at one endto an upper opening of the gas conduit 80 and at the other end to aprocess gas supplier 82. Moreover, a gas ejection opening 86 is formedat the center portion of the quartz plate 52 and open to the chamber 10.In a first process gas introduction portion 88 having the aboveconfiguration, the process gas from the process gas supplier 82 flowsthrough the first gas supplying pipe 84 and the gas conduit 80 in thecoaxial pipe 66, and is ejected from the gas ejection opening 86 towardthe susceptor 12 located below the gas ejection opening 86. The ejectedprocess gas is spread outward in a radial direction in the chamber 10,partly because the process gas is pulled toward the evacuation pathway18 surrounding the susceptor 12 by the evacuation apparatus 26. By theway, the first gas supplying pipe 84 is provided with a mass flowcontroller (MFC) 90 and an on-off valve 92 in the middle.

In this embodiment, a second process gas introduction portion 94 isprovided in addition to the first process gas introduction portion 88 inorder to introduce the process gas to the chamber 10. The second processgas introduction portion 94 includes a buffer chamber 96, plural sideejection holes 98, and a gas supplying pipe 100. The buffer chamber 98is shaped into a hollow ring that extends inside the side wall portionof the chamber 10 and along a circumferential direction of the side wallportion, and is located slightly lower than the quartz plate 52. Theplural side ejection holes 98 are open toward the plasma region in thechamber 10, arranged at equal angular intervals along an inner wall ofthe chamber 10, and in gaseous communication with the buffer chamber 96.The gas supplying pipe 100 connects the buffer chamber 96 to the processgas supplier 82. The gas supplying pipe 100 is provided with an MFC 102and an on-off valve 104 in the middle.

In the second process gas introduction portion 94, the process gas fromthe process gas supplier 82 is introduced into the buffer chamber 96 inthe side wall portion of the chamber 10 through the second process gassupplying pipe 100. Pressure in the buffer chamber 96 filled with theprocess gas becomes uniform along the circumferential direction of thebuffer chamber 96, which allows the process gas to be uniformly andhorizontally ejected from the plural ejection holes 98 toward the plasmaregion in the chamber 10. In this case, it may be difficult to uniformlydistribute the process gas ejected from the ejection holes 98 above thewafer W, because the process gas is pulled toward the evacuation ports22 when the process gas flows over the evacuation pathway 18. However,since the process gas ejected from the gas ejection opening 86 locatedat the center of the quartz plate 52 is spread in an outward radialdirection and flows toward the evacuation pathway 18 as stated above,the process gas ejected from the side ejection holes 98 is not affectedto a great extent by the evacuation apparatus 26 in this embodiment.Therefore, the plasma can be uniformly distributed above the wafer W onthe susceptor 12.

By the way, the process gases introduced into the chamber 10respectively from the first process gas introduction portion 88 and thesecond process gas introduction portion 94 may be the same, ordifferent. Flow rates of the gases can be controlled by the MFCs 90 and102, respectively, or the gases are introduced into the chamber at apredetermined flow rate ratio, so that the gases and thus the plasma areuniformly distributed in the radial direction.

Referring to FIG. 2, the waveguide pipe-coaxial pipe converter 64 andthe coaxial pipe 66 are shown in detail. The inner conductor 68 is madeof, for example, aluminum. The gas conduit 80 penetrates the innerconductor 68 along a center axis of the inner conductor 68. In addition,a cooling medium conduit 106 is foamed in parallel with the gas conduit80. The cooling medium conduit 106 includes an incoming path 106 a andan outgoing path 106 b that are divided by a vertical partition (notshown). In the upper portion of the inverse cone portion 68 a, a pipe108 is connected to the incoming path 106 a of the cooling mediumconduit 106. The opposite end of the pipe 108 is connected to a chillerunit (not shown). In addition, a pipe 110 is connected to the outgoingpath 106 b of the cooling medium conduit 106. The opposite end of thepipe 110 is connected to the same chiller unit. With this configuration,a cooling medium or cooling water supplied from the chiller unit flowsdownward through the incoming path 106 a so as to reach the bottom ofthe incoming path 106 a and returns back upward through the outgoingpath 106 b so as to flow into the pipe 110. In such a manner, the innerconductor 68 may be cooled.

At the center of the RLSA 54, there is an opening 54 a into which thegas conduit 80 is fitted, as shown in FIG. 2. In addition, the opening54 a is located in coaxial alignment with the gas ejection opening 86 ofthe quartz plate 52. With this configuration, the electromagnetic waves(microwaves) radiated from the RLSA 54 do not reach the gas ejectionopening 86, and thus no discharging takes place in the gas ejectionopening 86. By the way, the gas ejection opening 86 may be branched intoplural holes in the quartz plate 52. The plural holes may be locatedwithin a certain range in the radial direction of the quartz plate 52.

FIG. 3 shows a slot pattern in the RLSA 54 in this embodiment. As shown,the RLSA 54 has plural slots distributed in concentric circles.Specifically, two kinds of slots 54 b, 54 c whose longitudinaldirections are substantially at right angles are distributed inalternating concentric circles. These concentric circles are arranged atradial intervals depending on wavelengths of the microwaves propagatingin the radial direction of the RLSA 54. According to such a slotpattern, the microwaves are converted into circularly polarized planarwaves having two polarization components intersecting with each other,and the planar waves are radiated from the RLSA 54. The RLSA 54configured as described above is advantageous in that the microwaves maybe uniformly radiated into the chamber 10 (FIG. 1) from substantiallythe entire region of the antenna, and suitable to generate nonuniformand stable plasma.

By the way, various operations of the evacuation apparatus 26, the RFpower supplier 30, the switch 42 of the DC power supplier 40, themicrowave generator 60, the process gas introduction portions 88, 94,the chiller units (not shown), and the thermal conduction gas supplyingportion (not shown), and total operations as a whole are controlled by acontrolling portion (not shown) composed of, for example, amicrocomputer in the microwave plasma etching apparatus 1 according tothe first embodiment of the present invention.

In order to carry out an etching process in this microwave plasmaetching apparatus 1, the gate valve 28 is opened, and a wafer Wsubjected to the etching process is transferred into the chamber 10 andplaced on the electrostatic chuck 36. Then, etching gases (generally,mixed gases) are introduced at predetermined flow rates and apredetermined ratio from the first process gas introduction portion 88and the second process gas introduction portion 94, respectively. Atthis time, the chamber 10 is evacuated by the evacuation apparatus 26 sothat the inner pressure of the chamber 10 becomes at a set pressure. Inaddition, the RF power source 30 is activated in order to output the RFwaves at a predetermined power level to the susceptor 12 through thematching element 32 and the power feeding rod 34. Moreover, the switch42 is turned on in order to apply the DC voltage from the DC voltagesupplier 44 to the electrode 36 a of the electrostatic chuck 36, bywhich the wafer W is firmly held on the electrostatic chuck 36. Then,the microwave generator 60 is turned on in order to apply the microwavesto the RLSA 54 through the microwave transmission line 58, and thus themicrowaves are introduced into the chamber 10 from the RLSA 54 throughthe quartz plate 52.

The etching gases introduced into the chamber 10 from the gas ejectionopening 86 of the first process gas introduction portion 88 and the sideejection holes 98 of the second process gas introduction portion 94diffuse below the quartz plate 52 and are ionized by the microwaveenergy radiated from the surface waves (microwaves) propagating alongthe lower surface of the quartz plate 52, and thus the surface plasma isgenerated. Then, the plasma generated below the quartz plate 52 diffusesdownward so as to etch a film on the wafer W in an isotropic manner withradicals in the plasma, or to vertically etch the film by irradiation ofions in the plasma.

In the microwave plasma etching apparatus 1 as the microwave plasmaetching apparatus, high density plasma is generated through surface waveexcitation, so that the electron temperature of the plasma near thewafer W on the susceptor 12 is as low as about 0.7 through about 1.5 eV.Therefore, ion irradiation energy is reduced, thereby alleviating damageto the film to be etched. In addition, because the microwave energy isintroduced in a large area through the RLSA 54, the plasma etchingapparatus can easily process large size wafers. Moreover, since the gasconduit 80 is made to pass through the inner conductor 68 of the axialpipe 66, which is an end portion of the microwave transmission line 58,and the process gas is introduced into the chamber 10 from the gasejection opening 86 through the gas conduit 80, plasma densityuniformity and thus over-the-wafer uniformity of the etching rate can beimproved without any adverse effects of reduced antenna performance andabnormal discharging.

In addition, since the microwave plasma etching apparatus 1 generatesthe microwave plasma without applying a magnetic field to the chamber10, the need for a magnetic field generation mechanism including apermanent magnet, a magnetic coil, or the like can be eliminated, sothat the microwave plasma etching apparatus has a simple configuration.Even so, the plasma etching apparatus according to the embodiment may beanother type of plasma etching apparatus employing, for example,Electron Cyclotron Resonance (ECR).

Referring to FIG. 4, an ECR plasma process apparatus includes a magnetfield generation mechanism 112 having a permanent magnet or a magneticcoil around the chamber 10. The magnetic field generation mechanism 112can apply a magnetic field to a plasma generation space in the chamber10 so that the frequency of the microwaves is equal to the electroncyclotron frequency at any point in the plasma generation space, bywhich high density plasma can be generated. The magnetic field may be875 Gauss in the case of 2.45 GHz.

By the way, the second process gas introduction portion 94 (FIG. 1) canbe omitted, as shown in FIG. 4, while the first process gas introductionportion 88 is employed in order to introduce the process gas from theupper center portion (the gas ejection opening 86) of the chamber 10.

In addition, a hollow space formed in the inner conductor 68 of thecoaxial pipe 66, which corresponds to the gas conduit 80 in FIG. 2, maybe used for other purposes in other embodiments according to the presentinvention. Referring to FIG. 5, a monitor portion 114 is located abovethe inverse cone portion 68 a, and the hollow space of the innerconductor 68 serves as an optical measurement line through which theplasma process is monitored by the monitor portion 114. For example, inorder to detect an end point of plasma etching, the plasma spectrum maybe observed by the monitor portion 114 through an optical fiber probe(not shown) that is inserted into the hollow space located at the uppercenter portion of the chamber 10, and analyzed by spectrometry. Withthis, the end point can be known when a peak intensity of a particularemission originating from a particular gas specie is increased ordecreased. In addition, the hollow space of the inner conductor 68 maybe used as a light path through which a laser beam propagates, in orderto measure the thickness of an antireflection film or a resist film onthe wafer W. Moreover, a temperature sensor having the thermocouple atthe distal end may be inserted through the hollow space of the innerconductor 68 in order to measure a temperature at and around the uppercenter portion of the chamber 10.

In addition, the inner conductor 68 of the coaxial pipe 66 may havedifferent conduits from the conduit 80. For example, a plural pipeconfiguration employing, for example, a double pipe may be employed inthe inner conductor 68 of the coaxial pipe 66, instead of the gasconduit 80. In this case, each pipe of the plural pipes can be used asan independent line (a gas supplying line, a measurement line, or thelike). Moreover, a third process gas introduction portion may beprovided to the plasma etching apparatus 1 according to this embodimentof the present invention, in addition to or instead of the first and thesecond process gas introduction portions 88, 94, in order to introducethe process gasses into the chamber 10.

In addition, various alterations and modifications can be made to eachcomponent or member or their functions described above. For example,another type slot antenna can be used instead of the RLSA 54.Especially, when large plasma area is not required, the microwaves maybe introduced into chamber not through an antenna but through a duct,which may be referred to as a microwave injection method. Moreover, themicrowave transmission line 58 may be differently configured. Forexample, another transmission line may be inserted between the microwavegenerator 60 and the waveguide pipe 62 having a square-shaped opening.In addition, a circular pipe may be used instead of the waveguide pipe62. Moreover, the inverse cone portion 68 a of the converter 64 may bemade into a ridge guide shape instead of the door knob shape.Furthermore, a circular waveguide pipe may be electromagneticallycoupled to the chamber 10 without employing the converter 64.

Second Embodiment

Referring to FIGS. 6 through 9, a plasma process apparatus according toa second embodiment of the present invention is described. FIG. 6 is aschematic cut-open view of the plasma process apparatus 2 according tothe second embodiment of the present invention. While the plasma processapparatus 2 according to the second embodiment is operated, when etchingthe wafer W in substantially the same manner as the plasma processapparatus 1 according to the first embodiment, the plasma processapparatus 2 is different in a gas ejection configuration at the topcenter portion of the chamber 10 from the plasma process apparatus 1according to the first embodiment of the present invention. Thefollowing explanation is focused on the difference.

As shown in FIG. 6, the gas conduit 80 goes through the inner conductor68 of the coaxial pipe 66, and the top portion of the gas conduit 80 isconnected to the process gas supplier 82 through the first gas supplyingpipe 84, which places the gas conduit 80 in gaseous communication withthe first gas supplying pipe 84. In addition, a conductive injectorportion 110 is connected to the lower portion of the inner conductor 68so as to be in gaseous communication with the gas conduit 80. Theinjector portion 110 penetrates the quartz plate 52 and protrudesdownward from the lower surface of the quartz plate 52. In addition, theinjector portion 110 has a gas ejection opening 110 a at the bottom end,through which the process gas is ejected into the chamber 10.

In a first process gas introduction portion 88 having such aconfiguration, the process gas supplied at a predetermined pressure fromthe process gas supplier 82 flows through the first gas supplying pipe84, the gas conduit 80, and the injector portion 110 in this order, andis ejected into the plasma region in the chamber 10 from the gasejection opening 110 a of the injector portion 110. By the way, thefirst process gas supplying pipe 84 has a mass flow controller (MFC) 90and an open/close valve 92.

Referring to FIG. 7, the coaxial pipe 66 and the injector portion 110are shown in detail. The inner conductor 68 of the coaxial pipe 66 ismade of, for example, aluminum, and has the gas conduit 80 penetratingthe inner conductor 68 along a center axis of the inner conductor 68.The injector portion 110 is also made of, for example, aluminum, and hasa gas conduit 112 in gaseous communication with the gas conduit 80 inthe inner conductor 68 of the coaxial pipe 66. By the way, the first gassupplying pipe 84 may be made of a metal (or conductor), or a resin (orinsulator).

The injector portion 110 is composed of an upper half portion 114 havinga large diameter and a lower half portion 116 having a small diameter.The upper half portion 114 is fitted into a concave portion 118 formedin the quartz plate 52, and the lower half portion 116 is inserted intoa through hole 120 that extends from the center bottom of the concaveportion 118 through the lower surface of the quartz plate 52. A sealmember 122 such as an O ring is sandwiched by the upper half portion 114and the bottom surface of the concave portion 118, and thus hermeticallyseal the upper half portion 114 relative to the concave portion 118 (thequartz plate 52). By the way, the coaxial pipe 66 and the injectorportion 110 are preferably arranged along a normal line passing througha center of axial symmetry, or the center of RLSA 54 (the chamber 10 andthe susceptor 12).

As shown in FIG. 7, an upper portion of the injector portion 110contacts an opening 54 a of the RLSA 54. Therefore, the injector portion110 can be grounded via the RLSA 54 and the chamber. 10, or through theinner conductor 68 of the coaxial pipe 66, the outer conductor 70, theantenna back surface plate 72, and the chamber 10 in this order. Inaddition, the lower half portion 116 having the smaller diameterprotrudes downward from the through hole 120 of the quartz plate 52 intothe chamber 10. A protrusion distance d of the lower half portion 116(or, the distance between the gas ejection opening 110 a and the lowersurface of the quartz plate 52) may be about 10 mm or more, for reasonsdescribed below.

As stated above, the gas conduit 80 goes through the inner conductor 68of the axial pipe 66, which is an end portion of the microwavetransmission line 58. In addition, the conductive injector portion 110,which is in gaseous communication with the gas conduit 80, is connectedto the lower end portion of the inner conductor 68 and grounded alongwith the inner conductor 68. Moreover, the injector portion 110penetrates the RLSA 54 and the quartz plate 52 so as to protrude intothe chamber 10.

With this configuration, since the inner conductor 68 and theelectrically conductive injector portion 110 through which the processgas flows from the process gas supplier 82 to the chamber 10 aregrounded through the chamber 10, the process gas is not exposed to themicrowaves before reaching the chamber 10. Therefore, no undesiredionization (abnormal discharging) takes place in the process gas flowpath from the process gas supplier 82 to the gas ejection openings 110a. Especially, the electric field inside the quartz plate 52 cannot beleaked to the gas conduit 112 in the injector portion 110, because thegas conduit 112 is shielded from the electric field by the injectorportion 110. Therefore, no abnormal discharging takes place inside thequartz plate 52. Accordingly, plasma characteristics such as the plasmageneration efficiency, plasma density distribution and the like can bestably maintained, thereby improving the process performance.Additionally, the quartz plate 52 is prevented from being deterioratedor damaged, thereby lengthening the operational service life of thequartz plate 52.

In addition, since the injector portion 110 protrudes into the chamber10 by an appropriate distance d, discharging can be prevented at the gasejection opening 110 a in this embodiment. As stated above, due to themicrowave energy radiated from surface waves propagating along the lowersurface of the quartz plate 52, the process gas molecules near the lowersurface are ionized so that the microwave plasma is highly concentratednear the lower surface of the quartz plate 52. However, the surface waveenergy is rapidly reduced only a slight distance away from the lowersurface of the quartz plate 52. A region of reduced surface wave energyis called a plasma diffusion region where active species generated inthe plasma can only diffuse. Namely, when the gas ejection opening 110 aof the injector portion 110 is located away from the lower surface ofthe quartz plate 52 and in the plasma diffusion region, the ionizationof the process gas is effectively prevented at the gas ejection opening110 a.

FIG. 8 shows an experimental result of a plasma density distributionalong a vertical direction (Z) in the microwave plasma process apparatus2 according to the second embodiment of the present invention. FIG. 9shows an experimental result of a plasma temperature distribution alonga vertical direction (Z) in the microwave plasma process apparatus 2according to the second embodiment of the present invention. From thesefigures, it is understood that any position at a distance about 10 mm ormore from the dielectric window (the quartz plate 52) is in the plasmadiffusion region. This is the reason why the protrusion distance d ofthe gas ejection opening 110 a is determined to be about 10 mm or more.However, when the protrusion distance d becomes larger, it becomesdifficult for the process gas ejected from the gas ejection opening 110a to flow upward and reach the quartz plate 52. Therefore, theprotrusion distance d is preferably about 30 mm or less. In addition,the gas ejection opening 110 a of the injector portion 110 is preferablylocated at a distance about 20 mm or more from the wafer W on thesusceptor 12, considering whether the lower end of the injector portion110 hinders the transfer of the wafer W into and out from the chamber10, affects the microwave distribution and RF bias applied to thesusceptor 12, which may affect an etching rate, and whether the distanceover which the process gas can diffuse above the wafer W is sufficientenough to obtain a desired process gas distribution.

By the way, while FIG. 7 shows that the process gas is ejected downwardfrom the gas ejection opening 110 a, the process gas may be ejectedhorizontally from the lower end portion of the injector portion 110, orin a radial direction of the chamber 10. In addition, a plural pipeconfiguration employing, for example, a double pipe may be employed inthe inner conductor 68 of the coaxial pipe 66. In this case, each pipeof the plural pipes can be used as an independent line (a gas supplyingline, a measurement line, or the like).

In the second embodiment, since the gas conduit 80 located in the innerconductor 68 of the coaxial pipe in order to introduce the process gasthrough the quartz plate (ceiling plate) 52 is used as part of the gassupplying line of the first process gas introduction portion 88, thethrough hole of the quartz plate 52 through which the gas supplying line(especially the injector portion 110) goes can be as short as possible,thereby reducing the probability of abnormal discharging.

However, the gas supplying line in the first process gas introductionportion 88 may be modified so that the gas supplying line does not gothrough the inner conductor 68 of the coaxial pipe 66. For example, thefirst gas supplying pipe 84 may be inserted from a side wall of thequartz plate 52 through an opening made in a side wall of the chamber 10and horizontally extended in the quartz plate 52, and may be bent at thecenter portion of the quartz plate 52 so as to protrude downward fromthe lower surface of the quartz plate 52 as shown in FIG. 10. Or, thefirst gas supplying pipe 84 may be connected to a side opening made inthe injector portion 110 inside the quartz plate 52. In these cases, atleast a portion of the first gas supplying pipe 84, the portion beinglocated inside the quartz plate 52, is made of an electricallyconductive material and grounded through the side wall of the chamber10.

As another modification example of the plasma process apparatus 2according to the second embodiment, the first gas supplying pipe 84,which is connected at one end to the process gas supplier 82, may gothrough the antenna back surface plate 72, the slow wave plate 56, theRLSA 54, and the quartz plate 52 in this order, rather than the innerconductor 68 of the coaxial pipe 66, although not shown. In this case,the first gas supplying pipe 84 may protrude at the other end downwardfrom the lower surface of the quartz plate 52. Or, the other end of thefirst gas supplying pipe 84 may be connected to the side opening made inthe injector portion 110 inside the quartz plate 52. In thisconfiguration, plural of the injector portions 110 may be axiallysymmetrically provided in a ring shape. By the way, at least a portionof the first gas supplying pipe 84, the portion being located inside thequartz plate 52, is made of an electrically conductive material andgrounded through the antenna back surface plate 72 or the RLSA 54.

As another modification, a third process gas introduction portion may beprovided to the plasma etching apparatus 2 according to this embodimentof the present invention, in addition to or instead of the first and thesecond process gas introduction portions 88, 94, in order to introducethe process gasses into the chamber 10. In addition, the second processgas introduction portion 94 (FIG. 1) can be omitted, while the firstprocess gas introduction portion 88 is employed in order to introducethe process gas from the upper center portion (the gas ejection opening86) of the chamber 10.

In addition, various alterations and modifications can be made to eachcomponent or member or their functions described above. For example,another type slot antenna can be used instead of the RLSA 54.Especially, when large area plasma is not required, the microwaves maybe introduced into the chamber not through an antenna but through aduct, which may be referred to as a microwave injection method.Moreover, the microwave transmission line 58 may be differentlyconfigured. For example, another transmission line may be insertedbetween the microwave generator 60 and the waveguide pipe 62 having asquare-shaped opening. In addition, a circular pipe may be used insteadof the waveguide pipe 62. Moreover, the converter 64 may include amember in a ridge guide shape, instead of the inverse cone portion 68 ain the door knob shape. Furthermore, a circular waveguide pipe may beelectromagnetically coupled to the chamber 10 without employing theconverter 64.

In addition, because the microwave plasma etching apparatus 2 accordingto the second embodiment of the present invention generates themicrowave plasma without applying a magnetic field to the chamber 10,the need for a magnetic field generation mechanism including a permanentmagnet, a magnetic coil, or the like can be eliminated, so that themicrowave plasma etching apparatus 2 has a simple configuration. Evenso, the plasma etching apparatus according to an embodiment of thepresent invention may be another type of plasma etching apparatusemploying, for example, Electron Cyclotron Resonance (ECR), as describedin reference to FIG. 4 in the first embodiment.

Embodiments according to the present invention are not limited to themicrowave plasma etching apparatus in the above embodiment, but may be aplasma chemical vapor deposition (CVD) apparatus, a plasma oxidationapparatus, a plasma nitriding apparatus, a plasma sputtering apparatus,or the like. In addition, a substrate subjected to a plasma process isnot limited to the semiconductor wafer, but may be various substratesfor use in fabricating a flat panel display, a photomask, a CDsubstrate, a printed substrate, or the like.

1. A plasma process apparatus that processes a substrate utilizingplasma, the plasma process apparatus comprising: a process chamber thathouses the substrate subjected to a predetermined plasma process in amanner that the substrate is capable of being input and output, and thatis capable of being evacuated to a reduced pressure; a microwavegenerator that generates microwaves for generating plasma; a waveguidepipe that transmits the microwaves from the microwave generator to theprocess chamber; a waveguide pipe/coaxial pipe converter connected toone end of the waveguide pipe; a coaxial pipe that forms a line throughwhich the microwaves are transmitted from the waveguide pipe-coaxialpipe converter to the process chamber, wherein an inner conductive bodyof the coaxial pipe has a hollow portion; and a process gas supplyingportion that supplied a process gas into the process chamber through thehollow portion of the inner conductive body of the coaxial pipe.
 2. Theplasma process apparatus of claim 1, further comprising: a susceptor onwhich the substrate is placed in the process chamber, and a dielectricwindow for introducing the microwaves into the process chamber, whereinthe dielectric window serves as a ceiling surface opposing thesusceptor.
 3. The plasma process apparatus of claim 2, wherein thedielectric window is provided with a gas ejection opening that is incommunication with the hollow portion of the inner conductive body. 4.The plasma process apparatus of claim 2 or 3, wherein the dielectricwindow is one of constituent elements of a planar antenna.
 5. The plasmaprocess apparatus of claim 4, wherein the planar antenna iselectromagnetically coupled to one end of the coaxial pipe.
 6. Theplasma process apparatus of claim 4 or 5, wherein the planar antenna isa slot antenna.
 7. The plasma process apparatus of claim 6, wherein theslot antenna is a radial line slot antenna.
 8. The plasma processapparatus of any one of claims 4 to 7, wherein the planar antenna isprovided around the inner conductive body of the coaxial pipe.
 9. Theplasma process apparatus of any one of claims 1 to 8, wherein thewaveguide pipe-coaxial pipe converter converts a transmission mode inthe waveguide pipe to a TEM mode in the coaxial pipe.
 10. The plasmaprocess apparatus of claim 9, wherein the waveguide pipe issquare-shaped, and wherein one end portion of the inner conductive bodyprotrudes into the square-shaped waveguide pipe, the protruding endportion being thicker along the protruding direction in the waveguidepipe-coaxial pipe converter.
 11. The plasma process apparatus of claim10, wherein the hollow portion penetrates the inner conductive body ofthe coaxial pipe so as to allow a process gas to enter the hollowportion from an inlet opening made in the protruding end portion of theinner conductive portion and to be ejected from a hole directed towardan interior of the process chamber.
 12. The plasma process apparatus ofany one of claims 1 to 11, wherein the inner conductive body of thecoaxial pipe includes a coolant conduit through which a coolant mayflow.
 13. The plasma process apparatus of any one of claims 1 to 12,wherein the process gas supplying portion includes a second gasintroduction portion that introduces a process gas into the chamberthrough a path that is different from a first gas introduction portionthat includes the hollow portion of the inner conductive body of thecoaxial pipe.
 14. The plasma process apparatus of claim 13, wherein thesecond gas introduction portion includes a side wall eject hole fromwhich the process gas is ejected toward a center portion of the processchamber.
 15. The plasma process apparatus of claim 13 or 14, wherein theprocess gas supplying portion includes a flow rate control portion forindividually controlling flow rate of the process gasses introduced intothe process chamber through the first gas introduction portion and thesecond gas introduction portion, respectively.
 16. The plasma processapparatus of any one of claims 2 to 15, further comprising a radiofrequency wave generator that applies radio frequency waves to thesusceptor in order to generate a self bias voltage in the susceptor. 17.The plasma process apparatus of any one of claims 1 to 16, furthercomprising a magnetic field producing portion that surrounds the processchamber so as to produce a magnetic field around the process chamber,thereby causing electron cyclotron resonance in the plasma in theprocess chamber.
 18. A plasma process apparatus in which a substratesubjected to a predetermined plasma process is housed in a processchamber that may be evacuated to a reduced pressure, and a process gasand microwaves are introduced into the process chamber so as to generateplasma from the process gas so as to perform the predetermined plasmaprocess on the substrate, the plasma process apparatus comprising: amicrowave transmission line that transmits the microwaves from amicrowave generator to the process chamber, wherein a predeterminedsection of the microwave transmission line, the section including oneend portion of the microwave transmission line, is formed of a coaxialline, and wherein an inner conductive body of the coaxial line is formedof a hollow pipe through which the process gas is introduced into theprocess chamber.
 19. A plasma process apparatus in which a substratesubjected to a predetermined plasma process is housed in a processchamber that may be evacuated to a reduced pressure, and a process gasand microwaves are introduced into the process chamber so as to generateplasma from the process gas so as to perform the predetermined plasmaprocess on the substrate, the plasma process apparatus comprising: amicrowave transmission line that transmits the microwaves from amicrowave generator to the process chamber, wherein a predeterminedsection of the microwave transmission line, the section including oneend portion of the microwave transmission line, is formed of a coaxialline whose inner conductive body is formed of a hollow pipe; and amonitor portion that monitors through the hollow pipe the plasma processperformed in the process chamber.
 20. The plasma process apparatus ofclaim 19, wherein the monitor portion includes a plasma emissionmeasurement portion that spectroscopically measures emission of theplasma in the process chamber.
 21. The plasma process apparatus of claim19, wherein the monitor portion includes an optical thicknessmeasurement portion that measures a thickness of a film on the substrateheld on a susceptor in the process chamber.
 22. The plasma processapparatus of claim 19, wherein the monitor portion includes atemperature sensor that measures temperature inside the process chamber.